Question

Long range radio transmission is possible when the radio waves are reflected from the ionosphere. For this to happen, the frequency of the radio waves must be in the range,
A. 80-150 MHz
B. 8-25 MHz
C. 1-3 MHz
D. 150-500 kHz

Answer 1

Hint: Study about the communication system. Learn under what condition this process works and how we can transmit signals from one point to another point. Learn the types of communication systems and try to analyse the broadcast communication.

Complete step by step answer:
communication can be defined as the process of transmission of information from one point to another. For a communication system to build we need a transmitter and a receiver. We have two types of communication systems which are point to point communication systems and another is broadcast.
In a broadcast system we use one transmitter and more than one receiver. A transmitter processes the incoming signal and makes it suitable for transmission through a channel.
A receiver receives the signal and extracts the message or contents from the signal at signal output.
For different broadcasting systems we have different frequency bands. For standard AM broadcast the frequency band is 540-1600 kHz. For FM broadcast the frequency range is from 88-108 MHz. For television broadcasting systems we have different ranges of frequencies depending on the type over 50 MHz to 900 MHz.
Sky wave propagation is used by short wave broadcast services in the frequency range of a 3 MHz to 40 MHz, long distance communication can be achieved by ionospheric reflection of radio waves. This is called sky wave propagation.
Long range radio transmission is possible when the radio waves are reflected from the ionosphere. For this to happen, the frequency of the radio waves must be in the range 8-25 MHz.

The correct option is (B).

Note:
In a point to point communication system we have only one sender and receiver. In broadcast communication we have one sender with more than one receiver. So, with the broadcast system we can send one signal to more than one receiver.